K5LOGIN - Online Linux Manual Page

Section : 5
Updated :
Source : 1.20.1
Note : MIT Kerberos

NAME

k5login − Kerberos V5 acl file for host access

DESCRIPTION

The .k5login file, which resides in a user's home directory, contains a list of the Kerberos principals. Anyone with valid tickets for a principal in the file is allowed host access with the UID of the user in whose home directory the file resides. One common use is to place a .k5login file in root's home directory, thereby granting system administrators remote root access to the host via Kerberos.

EXAMPLES

Suppose the user alice

had a .k5login file in her home directory containing just the following line:

bob@FOOBAR.ORG

This would allow bob

to use Kerberos network applications, such as ssh(1), to access

alice

's account, using

bob

's Kerberos tickets. In a default configuration (with

k5login_authoritative

set to true in

krb5.conf

), this .k5login file would not let

alice

use those network applications to access her account, since she is not listed! With no .k5login file, or with

k5login_authoritative

set to false, a default rule would permit the principal

alice

in the machine's default realm to access the

alice

account. Let us further suppose that

alice

is a system administrator. Alice and the other system administrators would have their principals in root's .k5login file on each host:

alice@BLEEP.COM

joeadmin/root@BLEEP.COM

This would allow either system administrator to log in to these hosts using their Kerberos tickets instead of having to type the root password. Note that because bob

retains the Kerberos tickets for his own principal,

bob@FOOBAR.ORG

, he would not have any of the privileges that require

alice

's tickets, such as root access to any of the site's hosts, or the ability to change

alice

's password.